This non-provisional application claims priority under 35 U.S.C. xc2xa7109(a) on Patent Application No. 2001-331874 filed in Japan on Oct. 30, 2001, which is herein incorporated by reference.
1. Field of the Invention
The present invention relates to an optical axis adjusting device for adjusting an optical axis of a headlamp in accordance with an inclined state of a vehicle.
2. Description of the Related Art
When an optical axis adjustment of a headlamp is insufficient, a driver of an oncoming vehicle may be dazzled by the headlamp.
Conventionally, various techniques for preventing a driver of an oncoming vehicle from being dazzled by a head light have been studied including adjusting of an optical axis of the headlamp in accordance with an inclined state of the vehicle with respect to the ground.
In this conventional art, a signal output from an ultrasonic sensor and reflected by the ground is received, so that a distance between the ultrasonic sensor and the ground is measured. The ultrasonic sensor measures the distance at the front and the rear of the vehicle, and the inclined state of the vehicle with respect to the ground is judged on the basis of a difference between the two distances. When a road surface is an unpaved road surface, the an accurate judgment of the inclined state of the vehicle with respect to the ground is regarded as being difficult, and the optical axis adjustment is prohibited.
However, there are circumstances, where the detection by the ultrasonic sensor cannot be accurately made because of a surrounding environment of the vehicle. For example, sound and rain may interfere with the distance detection. In the case of the sound, the sound and a signal wave output from the ultrasonic sensor may interfere with each other, causing its waveform to be distorted, and the signal wave received by the ultrasonic sensor becomes inaccurate.
In the case of rain, the reflectivity of the road surface to the signal wave output from the ultrasonic sensor is low, and the received signal wave can be inaccurate.
Accordingly, in the foregoing conventional art, in the case where the signal wave detected by the ultrasonic sensor may be inaccurate due to the surrounding environment, the judgment as to whether or not the road surface is the unpaved may become inaccurate, and therefore, the judgment of the optical axis adjustment of the headlamp may also become inaccurate.
The present invention has been conceived in view of the above circumstances, and its object is to provide an optical axis adjusting system for a headlamp, which utilizes and ultrasonic sensor for judging an inclined state of a vehicle and adjusting an optical axis of a vehicle headlamp, and in which the inclined state of the vehicle is accurately judged and the optical axis of the headlamp can be suitably adjusted.
In this invention, the inclined state of the vehicle with respect to the road surface is judged on the basis of the detection of the ultrasonic sensor, and the optical axis of the headlamp is adjusted from the judged inclined state. When a hindrance factor detection device for detecting an existence of a factor hindering the inclination detection by the ultrasonic sensor detects the hindrance factor, a control device suspends the optical axis adjustment of the headlamp.
According to the present invention, the optical axis of the headlamp is adjusted on the basis of the inclined state of the vehicle only when the ultrasonic sensor detects high accuracy data without the hindrance factor, and the optical axis adjusting device can be controlled with high accuracy.